Can people who have sex changes (male to female) get erections? And if so, do erections and intercourse feel the same as it would for someone who was born male and still identifies as male?

I started a Vegan diet 40 days ago. I have been very careful with everything I have been eating as far as ingredients are concerned. Since the start of my diet I have had absolutely no interest in sex and now I have a yeast infection. I would appreciate any advice or input you may offer. Thank you for your time.

I am sexually active and I have a boyfriend and I have been on the the pill (I have tried a few different brands) for about 21 months now and have always had some problems with my mood/personality/I've turned into a huge bitch since I have been on it. The pill I am on right now, Ortho-Tricyclen Lo, has given me the least problems with this but I strongly feel like I am still pretty psychotic (I know that more than pills has to be blamed for this but I know it must have something to do with it). I need to know if I should go off the pill and use condoms (which I don't want to do) or if I should try a different birth control method (I though the Copper IUD looked good but also kind of scary) or maybe if I just need therapy or something. I like being on the pill for other reasons but I am sort of freaked out by how I am sometimes.

Does the amount of estrogen in birth control pills (ex. low, high or moderate levels) have any effect on protection against pregnancy? For example, is it better to take a birth control pill with a higher level of estrogen than one of the newer "low dose" ones? Will the protection be the same?